Clinical and Geriatric Predictors of In-Hospital Mortality in Older Adults Admitted to Internal Medicine Wards: A Retrospective Observational Study

<b>Background</b>: Older adults who are hospitalized in internal medicine wards often present with a challenging interplay of multimorbidity and geriatric syndromes. The timely identification of clinical and geriatric predictors of in-hospital mortality is crucial for guiding individualized care pathways and ensure appropriate resource allocation. In this study, we investigate the prognostic impact of frailty, delirium-including its motor subtypes-and global comorbidity burden on in-hospital mortality in patients aged 70 years and older. <b>Methods</b>: We conducted a retrospective observational study including 556 consecutive patients aged ≥ 70 years who were admitted to the Internal Medicine Unit of the University Hospital of Parma from January 2019 to July 2019. Demographic, clinical, and geriatric data were collected within 48 h of admission, including Clinical Frailty Scale (CFS), Cumulative Illness Rating Scale (CIRS), and delirium diagnosis with the 4AT tool. Multivariate Cox and logistic regression analyses were performed, including sex-stratified models. <b>Results</b>: The median age was 85 years (IQR 80-89), 58% were female, and in-hospital mortality was 11% (n = 61). Non-survivors had higher rates of severe frailty (CFS ≥ 7: 39% vs. 16%, <i>p</i> < 0.001), prevalent delirium (20% vs. 4%, <i>p</i> < 0.001), hypokinetic delirium (20% vs. 5%, <i>p</i> < 0.001), liver disease (23% vs. 11%, <i>p</i> = 0.008), cancer (44% vs. 24%, <i>p</i> < 0.001), and dementia (43% vs. 29%, <i>p</i> = 0.026) and a higher CIRS severity index (≥3:55% vs. 31%, <i>p</i> < 0.001). In Cox regression, independent predictors of death were prevalent delirium (HR 4.66, 95% CI 2.42-8.96), CFS ≥ 7 (HR 2.26, 95% CI 1.32-3.87), CIRS-LIVER ≥ 2 (HR 2.05, 95% CI 1.18-3.56), and cancer (HR 1.83, 95% CI 1.07-3.14). Sex-stratified models showed that in males, prevalent delirium (HR 10.23) and cancer (HR 2.49) predicted mortality, whereas in females, hypokinetic delirium (HR 3.67) and CIRS-LIVER ≥ 2 (HR 2.75) were the strongest predictors. Logistic regression confirmed these associations and additionally identified anemia and CFS ≥ 7 in males and CIRS severity index ≥ 3 in females as significant risk factors. <b>Conclusions</b>: In elderly patients who are admitted to internal medicine wards, prevalent and hypokinetic delirium, severe frailty, and high comorbidity burden, particularly liver disease and cancer, are strong independent predictors of in-hospital mortality, with distinct sex-specific patterns. Early multidimensional geriatric assessment may improve risk stratification and guide targeted interventions.